In a technology disclosed in JP 2003-244801 A, when an overvoltage abnormality occurs in an electric power system including an electric power converter, the switching of the electric power converter is stopped so as to prevent application of an overvoltage to an element of the electric power converter. In a technology disclosed in JP 2011-10406 A, when a vehicle is in collision, the switching of the electric converter is performed so as to discharge a capacitor in the electric power system.
When connection between an electric power source and the electric converter is cut off due to collision of the vehicle, electrical power cannot be recovered by the electric power source, and an overvoltage abnormality may occur in the electric power system. In this case, when the switching of the electric converter is stopped as disclosed in JP-A-2003-244801, it becomes difficult to discharge the capacitor in the electric power system, and when the vehicle is in collision, as disclosed in JP-A-2011-10406, it becomes difficult to rapidly decrease a high voltage in the electric power system.
An object of the present invention is to properly control the switching of an electric converter depending on whether an overvoltage abnormality occurs and a vehicle is in collision.